A little less attitude would help here. You must understand, first, that this is my field, and I don’t think anyone else here can say that. I can help you understand this stuff.
I have two purposes in this particular conversation. First, I would like to understand what features of a study you think are useful in convincing creationists. You have not been forthcoming so far, perhaps not on purpose. Second, I want to help you understand the science. You seem to have a number of misconceptions, and I’m trying to figure out what they are so I can help you with them.
First, this is not a case of speciation. It’s a phylogenetic analysis. Of course, it implies that a certain minimum amount speciation must have happened, but that’s not the same thing. Second, it isn’t clear what you mean by “a mutually close connection to a hypothetical common ancestor”. I can’t even speculate on what you mean. Other than that phrase, all the examples I have mentioned fit your two criteria.
That certainly would help. But you have no idea how fast that radiation was, because the paper doesn’t discuss it.
Not clear, actually. There is an Eocene fossil that’s claimed to be a placental.
True for all the examples I have mentioned also.
That’s not a well-formed question. We haven’t found a common ancestral population.
What founders? More importantly, is any of this relevant to your goal of convincing creationists?